|
1 // Copyright (c) 1999-2009 Nokia Corporation and/or its subsidiary(-ies). |
|
2 // All rights reserved. |
|
3 // This component and the accompanying materials are made available |
|
4 // under the terms of "Eclipse Public License v1.0" |
|
5 // which accompanies this distribution, and is available |
|
6 // at the URL "http://www.eclipse.org/legal/epl-v10.html". |
|
7 // |
|
8 // Initial Contributors: |
|
9 // Nokia Corporation - initial contribution. |
|
10 // |
|
11 // Contributors: |
|
12 // |
|
13 // Description: |
|
14 // Declaration for Compression class |
|
15 // |
|
16 // |
|
17 |
|
18 #ifndef __EZCOMPRESSOR_H__ |
|
19 #define __EZCOMPRESSOR_H__ |
|
20 |
|
21 #include <e32base.h> |
|
22 #include <ezstream.h> |
|
23 #include <ezbufman.h> |
|
24 |
|
25 /** |
|
26 The CEZCompressor class provides in-memory compression functions, including integrity checks of the uncompressed data. |
|
27 This version of the library supports only one compression method (deflation). Compression can be done in a single step |
|
28 (using CompressL()) if the buffers are large enough (for example if an input file is mmap'ed), or can be done by repeated calls |
|
29 of the DeflateL() function. The source data is compressed to the target buffer (both source and target contained within |
|
30 the buffer manager argument), and various other arguments distinguish the different compression settings. |
|
31 |
|
32 Note: In this version of the library a windowBits value of 8 is unsupported due to a problem with the window size being |
|
33 set to 256 bytes. Although a value of 8 will be accepted by the CEZCompressor constructors, as it is being changed |
|
34 internally by Zlib from 8 to 9, it will not be possible to use the same value for decompression. This is because the |
|
35 Zlib functions called by the CEZDecompressor constructors do not make the same change internally and as a result a |
|
36 KEZlibErrData is returned when calling InflateL(). It is therefore advised that for this version of the library |
|
37 windowBits of 9 is used in place of 8. |
|
38 |
|
39 @publishedAll |
|
40 @released |
|
41 */ |
|
42 class CEZCompressor : public CEZZStream |
|
43 { |
|
44 public: |
|
45 /** Compression strategy - used to tune the compression algorithm */ |
|
46 enum TStrategy |
|
47 { |
|
48 /** Use for normal data */ |
|
49 EDefaultStrategy = Z_DEFAULT_STRATEGY, |
|
50 |
|
51 /** Use for data produced by a filter (or predictor) */ |
|
52 EFiltered = Z_FILTERED, |
|
53 |
|
54 /** Force Huffman encoding only (no string match) */ |
|
55 EHuffmanOnly = Z_HUFFMAN_ONLY |
|
56 }; |
|
57 |
|
58 /** Compression levels */ |
|
59 enum |
|
60 { |
|
61 EDefaultCompression = Z_DEFAULT_COMPRESSION, |
|
62 ENoCompression = Z_NO_COMPRESSION, |
|
63 EBestSpeed = Z_BEST_SPEED, |
|
64 EBestCompression = Z_BEST_COMPRESSION |
|
65 }; |
|
66 |
|
67 /** Window Bits - the base two logarithm of the window size (the size of the history buffer) */ |
|
68 enum |
|
69 { |
|
70 EMaxWBits = MAX_WBITS |
|
71 }; |
|
72 |
|
73 /** Memory level - specifies how much memory should be allocated for the internal compression state */ |
|
74 enum |
|
75 { |
|
76 EDefMemLevel = MAX_MEM_LEVEL |
|
77 }; |
|
78 |
|
79 /** Compression panic values */ |
|
80 enum |
|
81 { |
|
82 EDeflateInitlialiserError = EUnexpected + 1, |
|
83 EDeflateTerminated |
|
84 }; |
|
85 |
|
86 public: |
|
87 ~CEZCompressor(); |
|
88 |
|
89 IMPORT_C static CEZCompressor* NewLC(MEZBufferManager& aInit, TInt aLevel = EDefaultCompression, |
|
90 TInt aWindowBits = EMaxWBits, TInt aMemLevel = EDefMemLevel, TStrategy aStrategy = EDefaultStrategy); |
|
91 IMPORT_C static CEZCompressor* NewL(MEZBufferManager& aInit, TInt aLevel = EDefaultCompression, |
|
92 TInt aWindowBits = EMaxWBits, TInt aMemLevel = EDefMemLevel, TStrategy aStrategy = EDefaultStrategy); |
|
93 IMPORT_C static CEZCompressor* NewLC(MEZBufferManager& aInit, const TDesC8 &aDictionary, |
|
94 TInt aLevel = EDefaultCompression, TInt aWindowBits = EMaxWBits, TInt aMemLevel = EDefMemLevel, |
|
95 TStrategy aStrategy = EDefaultStrategy); |
|
96 IMPORT_C static CEZCompressor* NewL(MEZBufferManager& aInit, const TDesC8 &aDictionary, |
|
97 TInt aLevel = EDefaultCompression, TInt aWindowBits = EMaxWBits, TInt aMemLevel = EDefMemLevel, |
|
98 TStrategy aStrategy = EDefaultStrategy); |
|
99 |
|
100 IMPORT_C void ResetL(MEZBufferManager& aInit); |
|
101 |
|
102 IMPORT_C TBool DeflateL(); |
|
103 |
|
104 IMPORT_C static void CompressL(TDes8 &aDestination, const TDesC8 &aSource, TInt aLevel = EDefaultCompression); |
|
105 |
|
106 private: |
|
107 enum TDeflationState |
|
108 { |
|
109 ENoFlush, |
|
110 EFinish, |
|
111 EFinalize, |
|
112 ETerminated |
|
113 }; |
|
114 |
|
115 private: |
|
116 CEZCompressor(MEZBufferManager* aInit); |
|
117 void ConstructL(TInt aLevel, const TUint8* aDictionary, TInt aLength, TInt aWindowBits, TInt aMemLevel, TStrategy aStrategy); |
|
118 void ConstructL(TInt aLevel, TInt aWindowBits, TInt aMemLevel, TStrategy aStrategy); |
|
119 |
|
120 private: |
|
121 MEZBufferManager* iBufferInit; |
|
122 TDeflationState iDeflationState; |
|
123 }; |
|
124 |
|
125 #endif |
|
126 |
|
127 |